Made the subtitle editor store the DFXP language code correctly
Added ability to download all subtitles as DFXP.
More fixes for DFXP language code handling.

Instead of trying to fix the language code in the editor, fix it
whenever we load subtitles.

Add the xml:lang tag to the div as well as the tt element.  Refactored
the code to load empty subtitles slightly.
Merge remote-tracking branch 'origin/staging' into brightcove
Moved code to get DFXP for all languages into the Video class
Added code to handle the brightcove API for syncing
Hooked the Brightcove API code into the syncing system.

I think brightcove syncing is now working.

Also refactored the code to create kaltura/brightcove videos for the
test.  Using factoryboy is much nicer and can be used by other cases
as well.
Syncing fixes

Fixed the update_subtitles method call when resyncing videos.  Made it
so we don't try to sync when there's no public tip for a language.
Added button to delete feed (#1442)
Merge branch 'staging' into brightcove
Merge remote-tracking branch 'origin/staging' into brightcove
Don't try to sync to brightcove if the write token isn't set
Updated styling/layout sections of our DFXP (#1012)
Merge remote-tracking branch 'origin/staging' into brightcove
Fix attribute error (#1504)
Merge pull request #1506 from pculture/brightcove

Brightcove